My neurologist says SFN is alway non-length dependent. My two skin punch biopsies back up that claim because the percentage loss in epidural nerve fiber density was equal at the thigh and distal leg. The time interval was 13 years. I also had sever restless leg syndrome as a child along with muscle contractions in my chest as a teenager. None of the classic SFN symptoms showed until my mid40’s, when I was diagnosed with impaired glucose tolerance. It could be in my case and others that genetic and autoimmune factors conspire with metabolic dysregulation to cause SFN. I experienced tingling and sparks all over my body, including genitals, face, tongue and lips. I also suffer from dry eyes which could be dysautonomia. So far no issues with bladder and bowel.